Nasa simulates visit to asteroid on ocean floor

The US Space Agency, Nasa, has sent an international team of astronauts to the bottom of the sea.

The aim is to simulate a visit to an asteroid, which Nasa plans to do in 2020.

The project is called NEEMO (Nasa Extreme Environment Mission Operations) and the crew includes British astronaut Tim Peake. They are to spend two weeks on the bed of the ocean in an underwater lab, testing tools and techniques.